The invention concerns a method of controlling an apparatus for supplying air pressure to a patient suffering from sleep problems.
The invention also concerns an apparatus for supplying air pressure to a patient suffering from sleep problems.
These sleep problems are respiratory and tend to waken the patient inopportunely.
They are for example apnoeas, hypopnoeas, acoustic vibrations or snores, or limitation of the respiratory flow, due to a narrowing of the upper airways of the patient.
The document U.S. Pat. No. 5,458,137 describes a method and a device for controlling respiration in the case of sleep problems, which use multiple and variable pressure levels.
A pressure source supplies a breathable gas compressed at a relatively low pressure to the airways of the user.
Pressure sensors monitor the pressures and convert them into electrical signals.
The electrical signals are filtered and processed in order to extract specific characteristics such as the duration and energy levels.
If these characteristics exceed chosen duration and energy level thresholds beyond a minimum time period, the microprocessor indicates the presence of a sleep respiratory problem.
If a chosen number of these events appears during a chosen time period, the microprocessor adjusts the pressure supplied by the source.
The document U.S. Pat. No. 5,490,502 describes a method and an apparatus for optimizing the controlled positive pressure in order to minimize the air flow coming from a generator while ensuring that flow limitation in the airways of the patient does not take place.
Provision is made therein to detect flow limitation by analysing a respiratory flow wave.
As soon as the presence of a flow limitation has been analysed, the system determines an action to be performed for adjusting the controlled positive pressure.
The pressure is increased, reduced or maintained depending on whether flow limitation has been detected and according to the previous actions implemented by the system.
The documents U.S. Pat. No. 5,335,654, EP-A-661 071 and EP-A-651 971 should also be cited.